Summary: Zai Lab Limited saw its U.S.-listed shares increase after the U.S. Food and Drug Administration granted Fast Track Designation to zocilurtatug pelitecan (zoci) for use in patients with extrapulmonary neuroendocrine carcinomas (epNECs) who have progressed following standard first-line therapy. The designation covers the company’s Delta-like ligand 3 (DLL3)-targeting antibody-drug conjugate and follows an earlier Fast Track granted for extensive-stage small cell lung cancer in May 2025.
Zai Lab reported a 7.2% rise in its Nasdaq-traded stock on Monday after announcing the FDA decision. The Fast Track status applies specifically to zoci - an investigational, potential first-in-class DLL3-targeting antibody-drug conjugate intended for the treatment of epNECs, a group of aggressive neuroendocrine malignancies. The company noted that epNECs affect roughly 100,000 people worldwide and that there are currently no targeted therapies or approved standard-of-care options for previously treated disease.
The regulatory move is the second Fast Track granted to zoci. In May 2025 the FDA issued a similar designation for zoci in extensive-stage small cell lung cancer. Following the latest decision, Zai Lab said it is engaging with health authorities on a registrational plan for epNECs.
Clinical data referenced by the company include preliminary results from an ongoing multicenter Phase 1b/2 registration-enabling trial that were presented at the American Association for Cancer Research Annual Meeting last month. In the heavily pretreated cohort included in the presentation, zoci produced an objective response rate of 38.2%.
Safety findings reported from the study described a generally manageable profile. The only treatment-related adverse event of grade 3 or higher that occurred in more than one patient was a decrease in neutrophil count.
Fast Track designation is intended to expedite the development and review of drugs that address unmet medical needs or treat serious or life-threatening conditions. The designation can provide for more frequent interactions with the FDA to discuss clinical development strategies and may make a drug eligible for Accelerated Approval and Priority Review if applicable criteria are satisfied.
Zoci targets DLL3, a therapeutic target validated in small cell lung cancer and overexpressed across many neuroendocrine carcinomas. Zai Lab has outlined plans to initiate three registration-enabling studies across second-line small cell lung cancer, first-line small cell lung cancer, and epNEC, with the company targeting to have these studies underway by the end of 2026.
The company’s statement linked the regulatory milestone to its ongoing clinical program and planning with regulators as it advances zoci through registrational development.
Key points:
- Zai Lab shares rose 7.2% after the FDA granted Fast Track Designation to zoci for epNECs, a malignancy with no targeted therapies in previously treated disease - sectors impacted include biotech, pharmaceuticals, and healthcare markets.
- Preliminary Phase 1b/2 data showed a 38.2% objective response rate in heavily pretreated patients, with a manageable safety profile; neutrophil count decrease was the only grade 3+ treatment-related adverse event seen in more than one patient.
- This is the second Fast Track for zoci, following May 2025 designation for extensive-stage small cell lung cancer, and Zai Lab plans three registration-enabling studies across SCLC and epNEC by end-2026.
Risks and uncertainties:
- Clinical data cited are preliminary from an ongoing Phase 1b/2 trial; outcomes from later-stage studies remain to be determined - this affects biotech and healthcare investment assessments.
- While the safety profile was described as manageable, a grade 3 or higher decrease in neutrophil count occurred in more than one patient, representing a safety risk that could influence regulatory review or labeling.
- Fast Track status facilitates development and review but does not guarantee approval; regulatory decisions will depend on future trial results and discussions with health authorities.